metal-organic compounds
Bis(μ-2-hydroxymethyl-2-methylpropane-1,3-diolato)bis[dichloridotitanium(IV)] diethyl ether disolvate
aChemistry, Institute of Natural and Mathematical Sciences, Massey University at Albany, PO Box 102904 North Shore Mail Centre, Auckland, New Zealand, and bChemistry, Institute of Fundamental Sciences, Massey University at Albany, PO Box 102904 North, Shore Mail Centre, Auckland, New Zealand
*Correspondence e-mail: a.j.nielson@massey.ac.nz
The title complex, [Ti2Cl4{CH3C(CH2O)2(CH2OH)}2], lies across a centre of symmetry with a diethyl ether solvent molecule hydrogen bonded to the –CH2OH groups on either side of it. The TiIV atom is coordinated in a distorted octahedral geometry by a tripodal ligand and two terminal chloride atoms. There are three coordination modes for the tripodal ligand distinguishable on the basis of their very different Ti—O bond lengths. For the terminal alkoxo ligand, the Ti—O distance is 1.760 (1) Å, the asymmetric bridge system has Ti—O bond lengths of 1.911 (1) and 2.048 (1) Å. The Ti—O bond length for the alcohol O atom is the longest at 2.148 (1) Å.
CCDC reference: 972604
Related literature
For general background to Ti—O and Ti—Cl bonds, see: Gau et al. (1996); Wu et al. (1996). For closely related structures, see: Talbot-Eeckelaers et al. (2006); Chang et al. (1993); Salta & Zubieta (1997); Chen et al. (1997). For cluster compounds of this ligand type, see: Boyle et al. (1995); Delmont et al. (2000); Liu et al. (1990).
Experimental
Crystal data
|
|
Data collection: SMART (Siemens, 1995); cell SAINT (Siemens, 1995); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for publication: SHELXL97.
Supporting information
CCDC reference: 972604
10.1107/S1600536813031504/hg5360sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536813031504/hg5360Isup2.hkl
Using normal bench-top techniques for air-sensitive compounds, TiCl4 (1.25 g, 6.59 mmol) was cooled to dry-ice temperature and diethyl ether (50 ml) chilled to -20 °C was added. The mixture was warmed to room temperature, heated until all the yellow solid had dissolved and 1,1,1-tris(hydroxymethyl)ethane (2.2 g, 6.6 mmol) in diethyl ether (50 ml) was added to the rapidly stirred solution whereupon a dense colourless precipitate was formed. The mixture was refluxed for 3 h, cooled to room temperature and the remaining solid allowed to settle and the solution was filtered. The volume was reduced to ca 30 ml and the solution stood at -20 ° C whereupon a mass of crystalline colourless material was deposited. Found: C, 31.06; H, 6.15%. C14H30Cl4O6Ti2 (i.e. C10H20Cl4O6Ti2.diethyl ether) requires C, 31.61; H, 5.69%. A crystal was chosen from the mass and the X-ray
obtained. This molecule corresponded to C10H20Cl4O6Ti2.bis-diethyl ether.All H atoms (except H3) were included in calculated positions and refined using a riding model with Uiso = 1.2Ueq(C) for H on secondary C atoms and 1.5Ueq(C) for those on tertiary C atoms. C—H distances of 0.99Å and 0.96Å were assumed for tertiary C and secondary C atoms respectively. H3 was located on a difference map and its x, y, z co-ordinates and isotropic thermal parameter refined.
Data collection: SMART (Siemens, 1995); cell
SAINT (Siemens, 1995); data reduction: SAINT (Siemens, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).Fig. 1. ORTEP diagram of molecule, at the 50% probability level, showing the numbering system. Symmetry code: (i) -x + 1, -y + 1, -z + 1. |
[Ti2Cl4(C5H10O3)2]·2C4H10O | Z = 1 |
Mr = 622.10 | F(000) = 324 |
Triclinic, P1 | Dx = 1.462 Mg m−3 |
Hall symbol: -P 1 | Mo Kα radiation, λ = 0.71073 Å |
a = 7.9617 (3) Å | Cell parameters from 5595 reflections |
b = 9.6379 (4) Å | θ = 2–25° |
c = 10.5783 (5) Å | µ = 0.98 mm−1 |
α = 71.351 (1)° | T = 150 K |
β = 82.023 (1)° | Plate, colourless |
γ = 66.757 (1)° | 0.26 × 0.24 × 0.10 mm |
V = 706.60 (5) Å3 |
Siemens SMART CCD diffractometer | 2661 independent reflections |
Radiation source: fine-focus sealed tube | 2417 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.015 |
Area detector ω scans | θmax = 25.7°, θmin = 2.0° |
Absorption correction: multi-scan (Blessing, 1995) | h = −9→9 |
Tmin = 0.766, Tmax = 0.892 | k = −10→11 |
6510 measured reflections | l = 0→12 |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.022 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.061 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.04 | w = 1/[σ2(Fo2) + (0.0325P)2 + 0.2355P] where P = (Fo2 + 2Fc2)/3 |
2661 reflections | (Δ/σ)max < 0.001 |
152 parameters | Δρmax = 0.31 e Å−3 |
0 restraints | Δρmin = −0.27 e Å−3 |
[Ti2Cl4(C5H10O3)2]·2C4H10O | γ = 66.757 (1)° |
Mr = 622.10 | V = 706.60 (5) Å3 |
Triclinic, P1 | Z = 1 |
a = 7.9617 (3) Å | Mo Kα radiation |
b = 9.6379 (4) Å | µ = 0.98 mm−1 |
c = 10.5783 (5) Å | T = 150 K |
α = 71.351 (1)° | 0.26 × 0.24 × 0.10 mm |
β = 82.023 (1)° |
Siemens SMART CCD diffractometer | 2661 independent reflections |
Absorption correction: multi-scan (Blessing, 1995) | 2417 reflections with I > 2σ(I) |
Tmin = 0.766, Tmax = 0.892 | Rint = 0.015 |
6510 measured reflections |
R[F2 > 2σ(F2)] = 0.022 | 0 restraints |
wR(F2) = 0.061 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.04 | Δρmax = 0.31 e Å−3 |
2661 reflections | Δρmin = −0.27 e Å−3 |
152 parameters |
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. |
Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger. |
x | y | z | Uiso*/Ueq | ||
Ti | 0.58094 (3) | 0.61520 (3) | 0.39188 (2) | 0.01725 (9) | |
Cl1 | 0.74357 (5) | 0.59557 (5) | 0.19464 (4) | 0.02805 (11) | |
Cl2 | 0.47954 (5) | 0.88725 (4) | 0.35265 (4) | 0.02495 (10) | |
O1 | 0.43149 (13) | 0.59722 (11) | 0.56614 (9) | 0.0177 (2) | |
O2 | 0.76654 (13) | 0.57443 (12) | 0.48899 (10) | 0.0217 (2) | |
O3 | 0.66826 (14) | 0.32177 (13) | 0.70683 (10) | 0.0197 (2) | |
C1 | 0.4634 (2) | 0.65978 (17) | 0.66438 (14) | 0.0209 (3) | |
H1A | 0.3764 | 0.6490 | 0.7400 | 0.025* | |
H1B | 0.4384 | 0.7737 | 0.6237 | 0.025* | |
C2 | 0.6586 (2) | 0.57709 (17) | 0.71785 (15) | 0.0211 (3) | |
C3 | 0.7972 (2) | 0.60351 (19) | 0.60594 (15) | 0.0248 (3) | |
H3A | 0.7897 | 0.7137 | 0.5832 | 0.030* | |
H3B | 0.9221 | 0.5328 | 0.6382 | 0.030* | |
H3 | 0.721 (3) | 0.236 (3) | 0.737 (2) | 0.038 (6)* | |
C4 | 0.6997 (2) | 0.40296 (17) | 0.78961 (15) | 0.0227 (3) | |
H4A | 0.8288 | 0.3514 | 0.8178 | 0.027* | |
H4B | 0.6216 | 0.3934 | 0.8709 | 0.027* | |
C5 | 0.6733 (2) | 0.65305 (19) | 0.82181 (16) | 0.0296 (4) | |
H5A | 0.5924 | 0.6323 | 0.8981 | 0.044* | |
H5B | 0.6371 | 0.7672 | 0.7813 | 0.044* | |
H5C | 0.7997 | 0.6079 | 0.8522 | 0.044* | |
O11 | 0.89033 (14) | 0.03405 (12) | 0.82316 (10) | 0.0220 (2) | |
C11 | 0.7018 (2) | 0.0355 (2) | 1.01998 (16) | 0.0309 (4) | |
H11A | 0.7672 | 0.0891 | 1.0464 | 0.046* | |
H11B | 0.6635 | −0.0316 | 1.0999 | 0.046* | |
H11C | 0.5939 | 0.1143 | 0.9687 | 0.046* | |
C12 | 0.8258 (2) | −0.06469 (18) | 0.93561 (16) | 0.0276 (3) | |
H12A | 0.9306 | −0.1496 | 0.9889 | 0.033* | |
H12B | 0.7584 | −0.1142 | 0.9041 | 0.033* | |
C13 | 1.0030 (2) | −0.0498 (2) | 0.73231 (17) | 0.0305 (4) | |
H13A | 0.9318 | −0.0910 | 0.6945 | 0.037* | |
H13B | 1.1090 | −0.1401 | 0.7797 | 0.037* | |
C14 | 1.0679 (2) | 0.0633 (2) | 0.62220 (18) | 0.0375 (4) | |
H14A | 0.9624 | 0.1497 | 0.5732 | 0.056* | |
H14B | 1.1492 | 0.0074 | 0.5610 | 0.056* | |
H14C | 1.1343 | 0.1064 | 0.6609 | 0.056* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Ti | 0.01564 (14) | 0.01876 (14) | 0.01493 (14) | −0.00583 (10) | 0.00015 (10) | −0.00266 (10) |
Cl1 | 0.0258 (2) | 0.0379 (2) | 0.01864 (19) | −0.01292 (16) | 0.00543 (15) | −0.00699 (16) |
Cl2 | 0.0292 (2) | 0.01963 (18) | 0.0251 (2) | −0.01055 (15) | −0.00415 (15) | −0.00208 (14) |
O1 | 0.0167 (5) | 0.0178 (5) | 0.0160 (5) | −0.0040 (4) | 0.0002 (4) | −0.0047 (4) |
O2 | 0.0178 (5) | 0.0266 (5) | 0.0192 (5) | −0.0073 (4) | −0.0004 (4) | −0.0058 (4) |
O3 | 0.0222 (5) | 0.0149 (5) | 0.0202 (5) | −0.0041 (4) | −0.0047 (4) | −0.0046 (4) |
C1 | 0.0239 (7) | 0.0196 (7) | 0.0181 (7) | −0.0051 (6) | 0.0006 (6) | −0.0084 (6) |
C2 | 0.0241 (7) | 0.0200 (7) | 0.0196 (7) | −0.0070 (6) | −0.0026 (6) | −0.0070 (6) |
C3 | 0.0248 (8) | 0.0308 (8) | 0.0221 (8) | −0.0129 (6) | −0.0025 (6) | −0.0078 (6) |
C4 | 0.0273 (8) | 0.0217 (7) | 0.0188 (7) | −0.0074 (6) | −0.0051 (6) | −0.0057 (6) |
C5 | 0.0405 (9) | 0.0274 (8) | 0.0245 (8) | −0.0122 (7) | −0.0050 (7) | −0.0108 (7) |
O11 | 0.0222 (5) | 0.0197 (5) | 0.0201 (5) | −0.0051 (4) | 0.0000 (4) | −0.0042 (4) |
C11 | 0.0341 (9) | 0.0376 (9) | 0.0224 (8) | −0.0189 (8) | 0.0021 (7) | −0.0046 (7) |
C12 | 0.0321 (9) | 0.0237 (8) | 0.0244 (8) | −0.0124 (7) | −0.0032 (7) | 0.0002 (6) |
C13 | 0.0270 (8) | 0.0294 (8) | 0.0296 (9) | −0.0014 (7) | −0.0008 (7) | −0.0130 (7) |
C14 | 0.0289 (9) | 0.0492 (11) | 0.0312 (9) | −0.0110 (8) | 0.0069 (7) | −0.0151 (8) |
Ti—O2 | 1.7601 (10) | C3—H3B | 0.9900 |
Ti—O1i | 1.9911 (10) | C4—H4A | 0.9900 |
Ti—O1 | 2.0478 (10) | C4—H4B | 0.9900 |
Ti—O3i | 2.1481 (11) | C5—H5A | 0.9800 |
Ti—Cl1 | 2.3184 (4) | C5—H5B | 0.9800 |
Ti—Cl2 | 2.3292 (4) | C5—H5C | 0.9800 |
Ti—Tii | 3.1649 (5) | O11—C13 | 1.4374 (19) |
O1—C1 | 1.4501 (17) | O11—C12 | 1.4413 (18) |
O1—Tii | 1.9911 (10) | C11—C12 | 1.502 (2) |
O2—C3 | 1.4243 (18) | C11—H11A | 0.9800 |
O3—C4 | 1.4473 (18) | C11—H11B | 0.9800 |
O3—Tii | 2.1481 (11) | C11—H11C | 0.9800 |
O3—H3 | 0.74 (2) | C12—H12A | 0.9900 |
C1—C2 | 1.533 (2) | C12—H12B | 0.9900 |
C1—H1A | 0.9900 | C13—C14 | 1.509 (3) |
C1—H1B | 0.9900 | C13—H13A | 0.9900 |
C2—C4 | 1.523 (2) | C13—H13B | 0.9900 |
C2—C3 | 1.533 (2) | C14—H14A | 0.9800 |
C2—C5 | 1.542 (2) | C14—H14B | 0.9800 |
C3—H3A | 0.9900 | C14—H14C | 0.9800 |
O2—Ti—O1i | 101.78 (5) | C2—C3—H3A | 109.1 |
O2—Ti—O1 | 86.71 (4) | O2—C3—H3B | 109.1 |
O1i—Ti—O1 | 76.83 (4) | C2—C3—H3B | 109.1 |
O2—Ti—O3i | 172.39 (5) | H3A—C3—H3B | 107.9 |
O1i—Ti—O3i | 80.17 (4) | O3—C4—C2 | 112.55 (12) |
O1—Ti—O3i | 86.59 (4) | O3—C4—H4A | 109.1 |
O2—Ti—Cl1 | 97.18 (4) | C2—C4—H4A | 109.1 |
O1i—Ti—Cl1 | 93.21 (3) | O3—C4—H4B | 109.1 |
O1—Ti—Cl1 | 169.89 (3) | C2—C4—H4B | 109.1 |
O3i—Ti—Cl1 | 90.02 (3) | H4A—C4—H4B | 107.8 |
O2—Ti—Cl2 | 93.95 (4) | C2—C5—H5A | 109.5 |
O1i—Ti—Cl2 | 158.75 (3) | C2—C5—H5B | 109.5 |
O1—Ti—Cl2 | 90.05 (3) | H5A—C5—H5B | 109.5 |
O3i—Ti—Cl2 | 82.46 (3) | C2—C5—H5C | 109.5 |
Cl1—Ti—Cl2 | 98.956 (16) | H5A—C5—H5C | 109.5 |
O2—Ti—Tii | 95.24 (4) | H5B—C5—H5C | 109.5 |
O1i—Ti—Tii | 39.05 (3) | C13—O11—C12 | 112.91 (12) |
O1—Ti—Tii | 37.78 (3) | C12—C11—H11A | 109.5 |
O3i—Ti—Tii | 81.61 (3) | C12—C11—H11B | 109.5 |
Cl1—Ti—Tii | 132.238 (18) | H11A—C11—H11B | 109.5 |
Cl2—Ti—Tii | 125.940 (16) | C12—C11—H11C | 109.5 |
C1—O1—Tii | 124.13 (8) | H11A—C11—H11C | 109.5 |
C1—O1—Ti | 118.13 (8) | H11B—C11—H11C | 109.5 |
Tii—O1—Ti | 103.17 (4) | O11—C12—C11 | 108.69 (13) |
C3—O2—Ti | 138.33 (9) | O11—C12—H12A | 110.0 |
C4—O3—Tii | 126.66 (9) | C11—C12—H12A | 110.0 |
C4—O3—H3 | 106.5 (16) | O11—C12—H12B | 110.0 |
Tii—O3—H3 | 117.1 (16) | C11—C12—H12B | 110.0 |
O1—C1—C2 | 113.32 (11) | H12A—C12—H12B | 108.3 |
O1—C1—H1A | 108.9 | O11—C13—C14 | 108.13 (14) |
C2—C1—H1A | 108.9 | O11—C13—H13A | 110.1 |
O1—C1—H1B | 108.9 | C14—C13—H13A | 110.1 |
C2—C1—H1B | 108.9 | O11—C13—H13B | 110.1 |
H1A—C1—H1B | 107.7 | C14—C13—H13B | 110.1 |
C4—C2—C1 | 110.95 (12) | H13A—C13—H13B | 108.4 |
C4—C2—C3 | 112.76 (13) | C13—C14—H14A | 109.5 |
C1—C2—C3 | 110.72 (12) | C13—C14—H14B | 109.5 |
C4—C2—C5 | 107.06 (12) | H14A—C14—H14B | 109.5 |
C1—C2—C5 | 108.02 (12) | C13—C14—H14C | 109.5 |
C3—C2—C5 | 107.07 (13) | H14A—C14—H14C | 109.5 |
O2—C3—C2 | 112.41 (12) | H14B—C14—H14C | 109.5 |
O2—C3—H3A | 109.1 |
Symmetry code: (i) −x+1, −y+1, −z+1. |
D—H···A | D—H | H···A | D···A | D—H···A |
O3—H3···O11 | 0.74 (2) | 1.89 (2) | 2.6233 (14) | 168 (2) |
D—H···A | D—H | H···A | D···A | D—H···A |
O3—H3···O11 | 0.74 (2) | 1.89 (2) | 2.6233 (14) | 168 (2) |
Footnotes
‡Former address.
Acknowledgements
We are grateful to Massey University for the award of a Post-Doctoral Fellowship to CS, and to Ms T. Groutso of the University of Auckland for the data collection.
References
Blessing, R. H. (1995). Acta Cryst. A51, 33–38. CrossRef CAS Web of Science IUCr Journals Google Scholar
Boyle, T. J., Schwartz, R. W., Doedens, R. J. & Ziller, J. W. (1995). Inorg. Chem. 34, 1110–1120. CSD CrossRef CAS Web of Science Google Scholar
Chang, Y., Chen, Q., Khan, M. I., Salta, J. & Zubieta, J. (1993). J . Chem. Soc. Chem. Commun. pp. 1872–1874. CrossRef Web of Science Google Scholar
Chen, Q., Chang, Y. D. & Zubieta, J. (1997). Inorg, Chim. Acta, 258, 257–262. Google Scholar
Delmont, R., Proust, A., Robert, F., Herson, P. & Gourzerh, P. (2000). Chimie, 3, 147–155. CAS Google Scholar
Farrugia, L. J. (2012). J. Appl. Cryst. 45, 849–854. Web of Science CrossRef CAS IUCr Journals Google Scholar
Gau, H.-M., Lee, C.-S., Lin, C.-C. & Jiang, M.-K. (1996). J. Am. Chem. Soc. 118, 2936–2941. CSD CrossRef CAS Web of Science Google Scholar
Liu, S., Ma, L., McGowty, D. & Zubieta, J. (1990). Polyhedron, 9, 1541–1553. CSD CrossRef CAS Web of Science Google Scholar
Salta, J. & Zubieta, J. (1997). Inorg. Chim. Acta, 257, 83–88. CSD CrossRef CAS Web of Science Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Siemens (1995). SAINT and SMART. Siemens Analytical X-ray Instruments Inc., Madison, Wisconsin, USA. Google Scholar
Talbot-Eeckelaers, C. E., Rajaraman, G., Cano, J., Aromí, G., Ruiz, E. & Brechin, E. K. (2006). Eur. J. Inorg. Chem. pp. 3382–3392. Google Scholar
Wu, Y.-T., Ho, Y.-C., Lin, C.-C. & Gau, H.-M. (1996). Inorg. Chem. 35, 5948–5952. CSD CrossRef CAS Web of Science Google Scholar
This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.
Transition metal complexes that arise from the tris-hydroxymethyl ethane ligand CH3C(CH2OH)3 are not widely reported in the literature. Structures identified by X-ray crystallography include the triply deprotonated form in cluster compounds of molybdenum and tungsten (Liu et al. 1990; Delmont et al. 2000) and dimeric and cluster compounds of chromium (Talbot-Eeckelaers et al. 2006), the doubly deprotonated form in dimeric vanadium-oxo complexes (Chang et al. 1993; Salta & Zubieta 1997) and the fully protonated form in monomeric yttrium complexes (Chen et al. 1997). For titanium only µ3–O and µ2–O coordination modes have been identified (Boyle et al. 1995).
When TiCl4 in diethyl ether was reacted with a mixture of CH3C(CH2OSiMe3)3 and CH3C(CH2OSiMe3)2(CH2OH) we obtained a small amount of colourless crystals analysing as TiCl2[(OCH2)2(HOCH2)CCH3]. 0.5 diethyl ether. One crystal was characterized by X-ray crystallography. The structure consists of a centrosymmetric dimer made up of two [(OCH2)2(HOCH2)CCH3] ligands forming a tripodal bridging system across two titanium atoms each of which also contain two terminal chloro ligands. One tripodal ligand is positioned above the two Ti atoms and out towards the rear of the molecule and the other is below and out the front with the two related by an inversion centre. The distorted octahedral geometry about Ti is made from one arm of a terminal alkoxo ligand (O2), another from an alcohol ligand (O3) and a third arm from the bridging alkoxo atoms (O1 and O1i). These latter each lie in trans-positions to the two cis-related chloro ligands.
For the terminal alkoxo ligand the Ti–O2 distance is 1.760 (1) Å which is indicative of strong π-bonding (see later). The asymmetric bridge system has Ti–O bond lengths of 1.991 (1) and 2.048 (7) Å and the Ti–Cl bonds trans to these bridging O atoms also show differences in length, 2.3184 (4) Å for Ti–Cl1 which is trans to the longer Ti–O1 and 2.3292 (4) Å for Ti–Cl2 which lies trans to the shorter Ti–O1i bond. The Ti–O bond length for the alcohol oxygen (Ti–O3) is the longest at 2.148 (1) Å. The strongly π-bonded terminal alkoxo ligand O atoms (O2, O2i) lie trans to the weak dative bonds made by the alcohol ligand O atoms (O3i, O3).
The overall coordination geometry and deprotonation features of the two ligands are identical with that found in the vanadium (v) complex {V2O2Cl2([(OCH2)2(HOCH2)CCH3]2} (Chang et al. 1993; Salta & Zubieta 1997). In {M2O4[(OCH2)3CCH3]2}2- (M = Mo, W) all three arms of the tripod are deprotonated (Liu et al. 1990; Delmont et al. 2000). Single deprotonation occurs in {Cr2Cl4([(OCH2)HOCH2)2(CEt]2} (Talbot-Eeckelaers et al. 2006).
The Ti–O bond lengths in the present complex reflect the various coordination modes in the molecule. The Ti–O1 bond lengths [1.991 (1) and 2.048 (1) Å] show the asymmetric nature of the bridging system across the two Ti atoms. The short Ti–O2 bond length [1.760 (1) Å] is associated with an alkoxo ligand. In comparison, terminal alkoxo ligand Ti–O bond lengths range from 1.702 (4) to 1.742 (6) Å in a variety of iso-propoxo Ti complexes (Gau et al. 1996). The dative nature of the alcohol ligand is shown by the longer Ti–O3 bond length [2.148 (1) Å] in the present complex being slightly longer than observed for isopropyl alcohol ligated to titanium [bond lengths 2.087 (4) and 2.093 (4) Å] (Wu et al. 1996). The Ti–Cl1 and Ti–Cl2 bond lengths [2.3184 (4) and 2.3292 (4) Å] do not differ significantly from each other and are typical of Ti–Cl bonds observed elsewhere. (Gau et al. 1996; Wu et al. 1996).
The strong π-donor nature of the alkoxo ligand oxygen is shown by the way other coordinated atoms push away from it [O2–Ti–O1, 86.71 (4); O2–Ti–O1i, 101.78 (5); O–2–Ti–Cl1, 97.18 (4); O2–Ti–Cl2, 93.95 (4)°]. For the dative Ti–O bond all the associated O3i–Ti–Y angles are 90° or below [range 80.17 (4) to 90.02 (3)°]. The bond angle associated with the bridging Ti–O1–Tii system [103.17 (4)°] does not differ significantly from comparable angles observed in other complexes. In this regard, it is noted that all known complexes have an alkoxo ligand making up the bridging system. The largest terminal Ti–O–C bond angle is associated with the alkoxo ligand [alkoxo Ti–O2–C3 angle 138.33 (9)° cf. alcohol Tii–O3–C4 angle 126.66 (9)°]. To accommodate the coordination mode of the various oxygen ligands across the two Ti atoms, the O–C–C bond angles of the tripod [range, 112.4 (1) to 113.3 (1)°] are slightly greater than the ideal tetrahedral angle.